Watercraft and related systems and methods

ABSTRACT

Embodiments of a watercraft are disclosed herein. One embodiment of a watercraft includes a board and a propulsion system secured to the board. The propulsion system has a water outlet portion and a water intake portion. The water intake portion includes a rim having a cross-sectional area that tapers along a length of the rim in a direction moving toward the water outlet portion. The propulsion system further includes a first blade having a first end connected to the rim and a second end opposite the first end. The second end of the first blade is a free floating end. The propulsion system also includes a first motor located between the water outlet portion and the water intake portion. The first motor has a first rotor component and a first stator component. The first rotor component is configured to rotatably drive the rim.

TECHNICAL FIELD

This disclosure relates generally to watercrafts, such as personal watercrafts. In particular, this disclosure relates, for example, to watercraft features, propulsion systems, and methods.

BACKGROUND

Personal watercrafts can be used for recreational purposes. With an aim to enhance the user experience, recently certain relatively smaller, personal watercrafts (e.g., single user watercrafts), which traditionally had been non-motorized watercraft, have been modified to include a motor. However, these types of motorized personal watercrafts tend to have unfavorable performance characteristics. For example, these types of motorized personal watercrafts can be unduly large and lack adequate power, while at the same time being difficult for a user to maneuver. As a result, these types of motorized personal watercrafts can fail to provide a desirable user experience.

SUMMARY

In general, various embodiments disclosed herein provide a watercraft having enhanced performance characteristics. For example, motorized watercraft embodiments disclosed herein can include one or more features that provide a combination of power (e.g., speed, acceleration), maneuverability (e.g., directional), and control (e.g., speed control) to facilitate a unique user experience. Embodiments of such motorized watercraft may generally include smaller, personal watercraft (e.g., single user watercrafts).

One exemplary embodiment includes a watercraft having a board and a propulsion system secured to the board. The board has a first side and a second side opposite the first side. The propulsion system has a water outlet portion and a water intake portion. The water intake portion includes a rim having a cross-sectional area that tapers along a length of the rim in a direction moving toward the water outlet portion. The propulsion system further includes a first blade having a first end connected to the rim (e.g., along the length of the rim as it tapers) and a second free floating end opposite the first end. The propulsion system also includes a first motor located between the water outlet portion and the water intake portion. The first motor has a first rotor component and a first stator component. The first rotor component is configured to rotatably drive the rim.

Another exemplary embodiment includes a watercraft having a board, first and second foot attachments, and a block. The board has a first side and a second side opposite the first side. The first foot attachment is on the first side of the board and adapted to secure a first foot of a rider to the board. The second foot attachment is on the first side of the board and adapted to secure a second foot of the rider to the board. The first foot attachment and the second foot attachment are spaced apart along a central longitudinal axis of the board. The block extends out from the first side of the board between the first foot attachment and the second foot attachment a distance from the first side of the board beyond the first foot attachment and the second foot attachment. The block has a first surface that is adapted to interface with a first leg of the rider and a second surface opposite the first surface that is adapted to interface with a second leg of the rider.

Additional exemplary embodiments can include methods of operating a watercraft. One such exemplary method embodiment includes, at a first step, securing a first foot at a first foot attachment on a first side of a board of the watercraft and securing a second foot at a second foot attachment on the first side of the board. The method can further include, at a second step, moving the board along a surface of water, for instance by actuating a speed control input to provide a motive force to the board via a propulsion system of the watercraft. The method can optionally include a step of maneuvering the watercraft while it is moving along the surface of the water, for instance using a block that extends out from a surface of the board between the first and second foot attachments. The method can optionally include a step of braking the watercraft as it is moving along the surface of the water. This could include, for instance, applying an external load (e.g., via the second leg of the user) at the second foot attachment located at a reduced width, rear portion of the board and submerging at least a portion of the rear portion of the board under the surface of the water. The method can further include, in one example, a step of reducing the speed of the watercraft along the surface of the water and while doing so progressively transitioning the watercraft's board from planing on the surface of the water to submerging under the surface of the water while the external load is applied to the watercraft.

The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

The following drawings are illustrative of particular embodiments of the present invention and therefore do not limit the scope of the invention. The drawings are not necessarily to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements.

FIG. 1 is a generally top perspective view of an exemplary embodiment of a watercraft.

FIG. 2 is a generally bottom perspective view of the exemplary embodiment of the watercraft in FIG. 1.

FIG. 3 is a cross-sectional view of an exemplary embodiment of a portion of a propulsion system for a watercraft, such as that illustrated in FIGS. 1 and 2.

FIG. 4 is a perspective view of an exemplary embodiment of a rim of the portion of the propulsion system shown in FIG. 3

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides some practical illustrations for implementing exemplary embodiments of the present invention. Examples of constructions, materials, and/or dimensions are provided for selected elements. Those skilled in the art will recognize that many of the noted examples have a variety of suitable alternatives.

FIGS. 1 and 2 illustrate an exemplary embodiment of a watercraft 10. FIG. 1 shows a perspective view of generally a first side of the embodiment of the watercraft 10 while FIG. 2 shows a perspective view of generally a second side of the embodiment of the watercraft 10. As will be described, the watercraft 10 can include one or more features that provide useful performance characteristics.

The illustrated exemplary watercraft 10 includes a board 12 and a propulsion system 14. The propulsion system 14 is secured to the board 12. The watercraft 10 can be self-propelled by the propulsion system 14. In use, the watercraft 10 can support a user (sometimes referred to as a “rider”) at the board 12 and provide a motive force, via the propulsion system 14, along the surface of a body of water. The user can maneuver, such as directionally, for instance by using the user's body weight, and control, such as by accelerating and/or braking, the watercraft 10 as desired during operation. In certain cases, the watercraft 10 has features and performance characterizes that allow the user to perform a variety of specialty maneuvers (e.g., “tricks” or “stunts”).

The board 12 defines a central longitudinal axis L₁ and further has a first side 16 (e.g., a “top” side) and a second side 18 (e.g., a “bottom” side). The first side 16 is opposite the second side 18. The first side 16 can define a deck surface of the board 12 and interface with (e.g., support) a user. The second side 18 can interface with the surface of a body of water and provide propulsion system 14 inlet(s) and outlet(s). The board 12 can be made of one or more materials. In one example, the board 12 is composed, at least in part, of a carbon fiber material.

The first side 16 can include a first foot attachment 20 and a second foot attachment 22. In the embodiment shown here, the first foot attachment 20 and the second foot attachment 22 are spaced apart a distance along the central longitudinal axis L₁ of the board 12. The first foot attachment 20 can be adapted to secure a first foot of a user to the board 12 while the second foot attachment 22 can be adapted to secure a second foot of the user to the board 12. Each of the first foot attachment 20 and the second foot attachment 22 can include a securing member 24 configured to hold the respective foot in place thereat. As shown in the illustrated example, the securing members 24 comprise bindings that can be strapped over a foot and appropriately tightened. In other examples, the securing members 24 can take a number of other forms. For instance, the securing members 24 could include a coupling configured to receive a corresponding mating coupling on an article of footwear (e.g., a riding shoe, boot, etc.).

In the embodiment shown, the first foot attachment 20 is located on a first platform 26 and the second foot attachment 22 is located on a second platform 28. The first platform 26 and the second platform 28 extend out from the first side 16 of the board 12 and are elevated above the deck surface of the board 12 defined by the first side 16. As illustrated, the first platform 26 and the second platform 28 are at a common elevation above the deck surface. But, in other embodiments, the first platform 26 can be at a different elevation relative to the deck surface than the second platform 28 (e.g., the first platform 26 can be at a greater elevation above the deck surface than the second platform 28). The platforms 26, 28 can, for example as shown, have a first end at the foot attachment 20, 22 locations and a second opposite end that attaches to the deck surface. This first end of the platforms 26, 28 may have a length, extending in a direction parallel to the central longitudinal axis L₁, which is greater than a length of this second end of the platforms 26, 28. The platforms 26, 28 can be made of one or more suitable materials and, for instance, can include a carbon fiber material.

In certain embodiments, the first side 16 of the board 12 can further include a block 30. When included in embodiments of the watercraft 10, the block 30 can provide stability and/or maneuverability to a user during operation of the watercraft 10. For example, the block 30 can be configured on the board 12 so as to extend between the legs of a user and thereby allow the user to grip the block 30 with the user's legs. This can serve to provide stability to the user while motive force is being supplied by the propulsion system 14. This may also allow the user shift body weight in order to maneuver the watercraft 10 as desired.

The block 30 can extend out from the first side 16 of the board 12 so as to be elevated above the deck surface of the board 12. As shown in the illustrated embodiment, the block 30 is located at an end of a neck 31 which extends between the deck surface of the board 12 and the block 30. As also shown in the illustrated embodiment, the block 30 extends out a distance from the first side 16 (e.g., via neck 31) that is beyond the first foot attachment 20 and the second foot attachment 22. Thus, an end of the block 30 can be at a greater elevation relative to the deck surface than the first foot attachment 20 and/or the second foot attachment 22. The block 30 can extend out from the first side 16 at a location along the central longitudinal axis L₁ that is between the spaced apart first foot attachment 20 and second foot attachment 22.

The block 30 may include a first surface 32 and a second surface 34 that is opposite the first surface 32. The first surface 32 can be adapted to interface with a first leg of the user and the second surface 34 can be adapted to interface with a second leg of the user. In the illustrated embodiment, the first surface 32 includes a first recessed (e.g., concave) region and the second surface 34 includes a second recessed region (e.g., concave). The block 30 can have a length, in a direction parallel to the central longitudinal axis L₁, which extends between the respective locations of the first and second foot attachments 20, 22 along the central longitudinal axis L₁. In this way, the first surface 32 can be aligned along the central longitudinal axis L₁ of the board 12 with the first foot attachment 20 and the second surface 34 can be aligned along the central longitudinal axis L₁ with the second foot attachment 22. This can allow the first leg of the user to interface with the first surface 32 while the first foot of the user is secured to the first foot attachment 20. Similarly, this can allow the second leg of the user to interface with the second surface 34 while the second foot of the user is secured to the second foot attachment 22. The block 30 can be made of a number of suitable materials. For example, the block 30 can be made of, at least in part, a foam (polyurethane) material, such as at the outer surface.

In some embodiments, one or more additional features can be includes at the block 30. For example, a handle 36 can be included on the block 30. The handle 36 can extend out from the block 30, for example in a direction opposite the board 12, as shown in the illustrated embodiment. When included, the handle 36 can provide further stability and/or maneuverability to a user, in addition to the block 30, during operation of the watercraft 10. As another example, a compartment 38 can be included within the block 30 and accessible via a lid 40. The lid 40 may seal to the compartment 38 in water-tight manner so as to prevent water from entering the compartment 38 during use of the watercraft 10.

The first side 16 of the board 12 can, in certain embodiments, also include one or more housings for a variety of the watercraft 10 components. For instance, the first side 16 can include a propulsion system housing 41. The propulsion system housing 41 can contain one or more propulsion system components, such as one or more motor parts, bearings, and/or battery units. The propulsion system housing 41 can be removably secured to the first side 16 (e.g., to the deck surface). In this way, the propulsion system housing 41 can be easily removed to facilitate maintenance related to propulsion system components or other watercraft 10 components. In one embodiment, the propulsion system housing 41 may include one or more ports, for instance to electrically connect to a battery unit therein for charging the battery unit.

As noted previously, the second side 18 of the board 12 can interface with the surface of a body of water. The second side 18 can include one or more fins 42. In the illustrated embodiment, two fins 42 are included at the second side 18. The fins 42 can be removable connected to the second side 18 such that different types of fins 42 can be conveniently interchanged at the second side 18. The fins 42 can extend out from the second side 18 and serve to provide stability to the board 12. In this embodiment, the fins 42 are located at a rear portion of the board 12. The fins 42 can increase in their extent outward from the second side 18 as the fins progress further rearward along the central longitudinal axis L₁.

Also include at the second side 18 can be a water intake portion 44 and a water outlet portion 46 of the propulsion system 14. As illustrated, the water intake portion 44 is spaced apart from the water outlet portion 46 a distance along the central longitudinal axis L₁. A motor 48 of the propulsion system 14 can be positioned between the water intake portion 44 and the water outlet portion 46. A fluid flow path can be defined by, and extend sequentially through, the water intake portion 44, motor 48, and water outlet portion 46. In some embodiments, such as that shown here, the second foot attachment 22 can be positioned along the central longitudinal axis L₁ closer to the water outlet portion 46 than the first foot attachment 20.

In the example shown, the water intake portion 44 includes a gradually sloping profile 45 a. Moving along the central longitudinal axis L₁ in a direction toward the water outlet portion 46, the water intake portion 44 extends progressively further outward from the second side 18. In this way, a proximal, or forward, portion of the water intake portion 44 extends outward from the second side 18 less than a distal, or rearward, portion of the water intake portion 44. This gradually sloping profile 45 a of the water intake portion 44 can be useful in allowing the watercraft 10 to pass over non-water surfaces (e.g., ramps, rails, etc.) without significant obstruction at the second side 18. In some embodiments, the water intake portion 44 can further include a radially narrowing profile 45 b, in a direction generally perpendicular to the sloping profile 45 a, moving along the central longitudinal axis L₁ in a direction toward the water outlet portion 46. In this way, an area defined within the water intake portion 44 can be reduced moving along the central longitudinal axis L₁ in a direction toward the water outlet portion 46.

Also in the example shown, the water outlet portion 46 includes a duct 47. The duct 47 may form a rearward portion of the propulsion system 14 and serve as an ejection point for the fluid flow path. The duct 47 can extend outward from the second side 18. In one example, the duct 17 can extend progressively further outward from the second side 18 moving along the central longitudinal axis L₁ in a direction a rearward end of the board 12. In some cases, the duct 47 can define an increasing an internal area moving along the central longitudinal axis L₁ in a direction a rearward end of the board 12.

The watercraft 10 can further include one or more controls that can be actuated by the user in order to operate aspects of the watercraft 10, such as the propulsion system 14. As one example, the watercraft 10 can include a speed control input. The speed control input can be actuated by a user to increase the motive force provided by the propulsion system 14. In one embodiment, the speed control input is located at the board 12, for instance at the block 30. In another embodiment, the speed control input is provided at a control unit that is remote from the board 12, for instance in the form of a hand-held remote control. In such an embodiment, the board 12 can include a transceiver configured to be in signal communication with the remote control unit (e.g., via Bluetooth protocol) as well as the propulsion system 14 such that the propulsion system 14 can be adjusted based on a control signal received from the remote control unit. In a further example, the transceiver at the board 12 can send signals to the remote control unit related to one or more status conditions (e.g., battery life) of the watercraft 10, and the remote control unit can output indications to the user related to the received status conditions.

In various embodiments, the watercraft 10 can be configured with a buoyancy that facilitates useful performance characteristics. In one embodiment, the watercraft 10 itself is positively buoyant in water (and thus will float) when stationary but the watercraft 10 is negatively buoyant in water (and thus will not float) when stationary and external loading is applied to the watercraft 10 (e.g., a user, for instance of average weight, is supported on the board 12). In other words, in such embodiment, the watercraft 10 has a buoyancy that is sufficient to float the watercraft 10 itself in water when stationary but the buoyancy of the watercraft 10 is insufficient to float the watercraft 10 in water when stationary and external loading is applied to the watercraft 10, such as when a user is on the board 12. Rather, in this embodiment, the ability of the watercraft 10 to move a user along the surface of a body of water results from the motive force being supplied by the propulsion system 14. Thus, as the speed of the watercraft 10 is reduced while a user is on the board 12, the watercraft 10 can begin to transition from planing along the surface of water to submerging at the board 12. This can be distinguishable from traditional wakeboards or other watercraft boards, where the buoyancy of such traditional boards counteracts and prevents submersion of the board (e.g., a top surface at a rear portion of the board) below the surface of the water.

In such embodiments, the geometry of the board 12 can be adapted to help provide the described buoyancy feature. As an example, the planing area of the board 12 can be minimalized at a rear portion (e.g., rear half, rear third, rear quarter, etc.) such that this planing area is reduced relative to a planing area at a central and/or front portion of the board 12. Such board 12 may correspondingly have a reduced water displacement. The minimalized planing area at the rear portion of the board 12 can be formed in one embodiment by a reduced width of the board 12 at the rear portion. Though in other embodiments various other design features can be implements, additionally or alternatively, to minimalize the planing area at the rear potion.

As illustrated, in one embodiment, the board 12 can include a region 50 having a reduced area, for example, resulting from a reduced width of the board 12. The central longitudinal axis L₁ of the board 12 can define a width of the board 12 extending generally perpendicular to the central longitudinal axis L₁. As shown in the illustrated example, the board 12 includes a first width at a region 52 and a second width at the region 50. Here, the second width at the region 50 is less than the first width at the region 52 and, as a result, the region 50 has a reduced area relative to the region 52. Moreover, the width of the board 12 tapers moving along the central longitudinal axis L₁ in a rearward direction (e.g., in a direction toward the water outlet portion 46) such that the width of the board 12 is less at a rear portion of the board 12 than at a central and/or front portion of the board 12.

As further shown in the illustrated example, the foot attachments 20, 22 are located at regions on the board 12 having different areas. In this example, the first foot attachment 20 is located on the board 12 at the region 52 while the second foot attachment 22 is located on the board 12 at the region 50. Thus, the second foot attachment 22 is located at a portion of the board 12—region 50—having a reduced width, and thus a reduced area relative to the first foot attachment 20—located at region 52.

The described buoyancy feature can provide the watercraft 10 with useful performance characteristics. This can include, for example, certain useful advantages in maneuvering and/or controlling the watercraft 10. For instance, the watercraft 10 can provide a braking feature while moving along the surface of water. Namely, the user can apply force to a rear region of the board 12 of reduced area (e.g., the region 50 at second foot attachment 22) to submerge a rear portion of the board 12 under water, thereby acting to brake the watercraft 10 while the rear portion is submerged. Likewise, the user can reduce the applied force at the region of the board 12 of reduced area to bring more of the rear portion of the board 12 above water. The can provide enhanced speed control of the watercraft 10 as well as more precise directional maneuvering of the watercraft 10.

Having described exemplary features of the watercraft 10 generally, various exemplary features pertaining to the propulsion system 14 will now be described.

FIG. 3 shows a cross-sectional view of an exemplary embodiment of a portion of the propulsion system 14 for use with the watercraft 10. A casing 100 can enclose all, or part of, the portion of the propulsion system 14 shown here. As noted, the propulsion system 14 can be secured to the board (as shown, e.g., in FIG. 2.). As one example, the casing 100 can be secured to the board. For instance, the casing 100 can sit at the first side of the board while an end of the water intake portion and an end of the water outlet portion (e.g., the duct) are at the second side of the board. In this way, a fluid flow path can extend from the end of the water intake portion at the second side of the board, through the portion of the propulsion system shown in FIG. 3 at the first side of the board, and out the end of the water outlet portion at the second side of the board. Such a configuration may be useful in reducing obstructions at the bottom side of the board.

The illustrated portion of the propulsion system 14 includes a rim 102, annular tube 104, stator tube 106, and propulsion system central longitudinal axis L₂. In operation, water enters the illustrated portion of the propulsion system 14 as shown at arrow D. A fluid flow path extends from the rim 102, through the annular tube 104, to the stator tube 106.

The rim 102 can be in fluid connection with an end of the water intake portion and, in some cases, can be considered to form part of the water intake portion. In the illustrated embodiment, the rim 102 and the annular tube 104 are attached to one another and are rotatable together. The rim 102 can include a flange 108 and the annular tube 104 can include a flange 110. The corresponding flanges 108, 100 can be secured together (e.g., via bolts, screws, etc.) to connect the rim 102 and the annular tube 104.

In some embodiments, the rim 102 can define a cross-sectional area that tapers along a particular length of the rim 102 in a direction moving toward the water outlet portion (e.g., toward the annular tube 104). For instance, as shown in FIG. 3, a first cross-sectional area of the rim 102 at an upstream portion is greater than a second cross-sectional area of the rim 102 at a downstream portion. In one example, the cross-sectional area of the rim 102 can progressively reduce at a constant rate moving along a length of the rim 102 toward the water outlet portion. As one non-limiting example, a diameter of the rim 102 at a first upstream end can be approximately six inches and a diameter of the rim 102 at a second downstream end can be approximately four inches. In this example, the diameter of the rim 102 can reduce continuously along a length of the rim moving along the central longitudinal axis L₂ from the first upstream end to the second downstream end. The second downstream end can be located at a position along the central longitudinal axis L₂ that coincides with one or more bearings 120 interfacing with the annular tube 104.

One or more blades 107 can be connected along a respective blade end to an interior surface of the rim 102. In certain embodiments, the respective blade end of the one or more blades 107 can extend along the length of the rim 102 that tapers in the direction moving toward the water outlet portion. With the one or more blades 107 connected to the interior surface of the rim 102, in the illustrated example an open fluid channel is present through a generally central portion of the rim 102. Thus, because the one or more blades 107 are connected to the rim 102, and rotatable by the rim 102, no shaft or hub needs to extend within the rim 102. Such a configuration can provide useful performance characteristics. For instance, this configuration can help to reduce cavitation and its related impact on performance of the propulsion system 14.

The stator tube 106 can be in fluid connection with an end of the water outlet portion (e.g., the duct) and, in some cases, can be considered to form part of the water outlet portion. The stator tube 106 can be attached in place at the propulsion system 14, such as at the casing 100 as shown in the illustrated embodiment. The stator tube 106 can extend at an angle relative to the central longitudinal axis L₂, for instance such that a central longitudinal axis of the stator tube 106 is non-parallel to the central longitudinal axis L₂. Furthermore, in some examples, the stator component 106 can include one or more blades 111 that can each have a geometry for efficiently directing water output for purposes of propulsion (e.g., corresponding to the angle at which the stator tube 106 extends relative to the central longitudinal axis L₂).

To drive the propulsion system 14, the propulsion system 14 includes one or more motors. In the illustrated embodiment, the propulsion system 14 includes three motors 48 a, 48 b, and 48 c. However, in other embodiments, any number of motors can be implemented depending on the particular application. Each motor 48 a, 48 b, and 48 c attaches to the annular tube 104 and acts to rotatably drive the annular tube 104, and thus the connected rim 102. In this example, the motors 48 a, 48 b, and 48 c are electrically powered motors. The motors 48 a, 48 b, and 48 c can be electrically connected to the one or more onboard battery units serving as input source to the motors 48 a, 48 b, and 48 c. Such motors 48 a, 48 b, and 48 c can be capable of applying torque quickly when desired, thereby providing a watercraft that can be capable of near instantaneous acceleration.

The motor 48 a can include a rotor component 112 and a stator component 114. The rotor component 112 and the stator component 114 can each be in the form of a ring shaped component, such that the motor 48 a itself can take the form of a generally ringed shaped component. The rotor component 112 and the stator component 114 can be positioned around the annular tube 104. Thus, the annular tube 104 can extend through the rotor component 112 and the stator component 114, and likewise the motor 48 a. The fluid flow path provided by the annular tube 104 can thereby extend through the rotor component 112 and the stator component 114.

The exemplary ring shaped rotor component 112 is rotatably driven relative to the exemplary ring shaped stator component 114. For instance, as one example the rotor component 112 can include a magnetic rotor assembly. The rotor component 112 can be rotatably mounted to the annular tube 104 by a moving mount 116. The stator component 114 can be mounted in place by static mount 118, which in turn can be secured to the casing 100 or other stationary component of the propulsion system 14. Thus, as the rotor component 112 is rotatably driven, relative to the stator component 114, it acts to rotatably drive the annular tube 104 and thus the rim 102. A number of bearings 120 can be included along the outer surface of the annular tube 104 to facilitate rotation of the annular tube 104.

The motors 48 b and 48 c can be the same as, or similar to, that described for the motor 48 a. Thus, in the illustrated embodiment, the propulsion system 14 can include a series of adjacent motors 48 a, 48 b, and 48 c interlocked together and located between the water intake portion and the water outlet portion. The rotor component of each motor 48 a, 48 b, and 48 c can be connected to the annular tube 104 and act to rotatably drive the annular tube 104, and thus the connected rim 102. The annular tube 104 can pass through an inner diameter of each of the motors 48 a, 48 b, and 48 c. In one exemplary configuration, the water flow path extends from the water intake portion, through the rim 102, into the annular tube 104 and through the series of motors 48 a, 48 b, and 48 c, to the stator tube 106, and out the water outlet portion. Such a configuration can provide a propulsion system 14 that is compact, lightweight, and efficient. Moreover, the location of the water flow path can be useful in cooling the motors 48 a, 48 b, and 48 c.

FIG. 4 shows a perspective view of the exemplary rim 102 of the portion of the propulsion system 14 shown in FIG. 3. The rim 102 can include an upstream end 130 and an opposite downstream end 132. As shown, the flange 108, for connecting to the annular tube, can be included at the downstream end 132. The rim 102 further includes an interior surface 134. The interior surface 134 extends from the upstream end 130 to the downstream end 132 and defines an interior diameter of the rim 102.

As noted previously, the rim 102 can include a number of blades 107. In the illustrated embodiment, the rim 102 includes three blades 107. However, in other embodiments any number of blades 107 can be included as appropriate for the particular application. Each blade 107 has a first end 136 and a second end 138 that is opposite the first end 136. The first end 136 can be connected to the interior surface 134 of the rim 102. As shown in illustrated example, the first end 136 is connected to the interior surface 134 along its length. As also shown in the illustrated embodiment, the second end 138 can be at a location within the rim 102 and be a free floating end. As such, the second end 138 is not connected to a hub of shaft within the rim 102. As a result, an open fluid channel is defined through a generally central portion of the rim 102 by each of the respective second free floating ends 138 of the blades 107.

As also noted previously, the rim 102 can define an interior diameter that reduces, and thus a cross-sectional area that likewise reduces, along a particular length (e.g., an entire length) of the rim 102 in a direction moving from the upstream end 130 toward to downstream end 132. One or more of the blades 107 can include a blade pitch that changes along a length of the interior surface 134 as the cross-sectional area of the rim 102 reduces. In the illustrated example, the blade pitch of the blades 107 increases as the first end 136 moves along the interior surface 134 in a direction from the upstream end 130 toward to downstream end 132. For instance, the increase in the blade pitch of the blades 107 can match the reduction in the cross-sectional area of the rim 102 moving in a direction from the upstream end 130 toward to downstream end 132.

The described configuration of the rim 102 and blades 107 can provide useful performance characteristics. For example, the decrease in the cross-sectional area of the rim 102 can act to accelerate water along the fluid flow path (e.g., along the open fluid channel defined by each of the respective second free floating ends 138 of the blades 107). Furthermore, the blades 107 within the rim 102 can act to augment the acceleration of the water along the fluid flow path. Moreover, during operation when the rim 102 is rotatably drive, water can be pushed from the open fluid channel, defined by each of the respective second free floating ends 138 of the blades 107, outward into the blades 107 and against the interior surface 134. The open fluid channel may help to reduce cavitation that generally could occur on the interior surface 134 of the rim 102 in prior systems utilizing a shaft or hub to drive the blades. This can result in a more efficient propulsion system 14.

In addition to exemplary watercraft features and related systems described up to this point, the present disclosure also encompasses methods of operating a watercraft. Such operating methods could, for example, be performed using a watercraft having one or more features as disclosed previously herein.

One exemplary embodiment of a method of operating a watercraft includes, at a first step, securing a first foot at a first foot attachment on a first side of a board of the watercraft and securing a second foot at a second foot attachment on the first side of the board. The second foot attachment can be spaced apart from the first foot attachment along the central longitudinal axis of the board. The first foot attachment can be located at a first portion of the board (e.g., at a central or forward portion of the board) having a first width and the second foot attachment can be located at a second portion of the board (e.g., a rear portion of the board) having a second width, where the second width is less than the first width.

The method can also include, at a second step, moving the board along a surface of water. This can include actuating a speed control input to provide a motive force to the board, via a propulsion system of the watercraft. Actuating the speed control input can cause the propulsion system to draw water in through a water intake portion, pass this water through a rotating rim having a cross-sectional area that reduces in a downstream direction, pass the water from the rim to a rotating annular tube which extends through an interior diameter of one or more motors (e.g., through annular rotor and stator components of the respective one or more motors), and output the water at a water outlet portion. The annular tube can be rotatably driven by the motor at a rate dictated by the speed control input. The rim can be connected to the annular tube and rotate with the annular tube at a rate as dictated by the speed control input. The rim can define an interior surface along which a number of blades extend as the cross-sectional area of the rim reduces in the downstream direction. The blades can be connected along the interior surface at a first end and terminate at a second opposite end that is free floating and defines an open fluid channel thorough a generally central portion of the rim. Actuating the speed control input can move water from the open fluid channel outward into the blades and against the interior surface of the rim.

The method can optionally include a step of maneuvering the watercraft while it is moving along the surface of the water. As one example, this step can include interfacing a first leg with a first surface of a block, which extends out from the first side of the board between the first and second foot attachments, and interfacing a second leg with a second surface of the block that is opposite the first surface of the block. Interfacing the first and second legs, respectively, with the first and second block surface can include positioning the first and second legs, respectively, at first and second recessed regions on the block. The first surface of the block can be aligned with the first foot attachment and the second surface of the block can be aligned with the second foot attachment. This step can, for instance, further include altering a direction orientation of the watercraft while the watercraft is moving along the surface of the water and the first and second legs, respectively, are interfacing with the first and second surfaces of the block. Thus, this can include altering the directional orientation of the watercraft using the block.

The method can optionally include a step of braking the watercraft as it is moving along the surface of the water. This step can include applying an external load (e.g., via the second leg of the user) at the second foot attachment located at a reduced planing area of the board (e.g., a reduced width portion of the board), for instance at a rear portion of the board, and thereby submerging at least a portion of the rear portion of the board under the surface of the water and thereby act to brake the watercraft while this portion is submerged. In one example, this step can including reducing the speed of the watercraft, once having done so shifting body weight to the reduced planing area of the board (e.g., the rear portion of the board), and submerging the rear portion of the board below the surface of the water to orient the board upward above the surface of the water at a front portion of the board. At this point water may be over the front side of the board at the rear portion while the bottom side of the board at the front portion is spaced a distance above the surface of the water. This step can in some cases be considered as complimentary to maneuvering the watercraft, since in some cases the described braking can provide useful maneuvering.

The method can further include, in one example, a step of reducing the speed of the watercraft along the surface of the water and progressively transitioning the watercraft's board from planing on the surface of the water to submerging under the surface of the water while an external load is applied to the watercraft (e.g., while a user is on the first surface of the board). This step can include progressively submerging previously planing regions of the board under the surface of the water, while the external load is applied, at a rate that corresponds to the rate at which the speed of the watercraft is reduced (e.g., the watercraft's rate of deceleration). In a further example, the method can include removing the external load from the watercraft and upon doing so floating the board of the watercraft on the surface of the water.

Although the present invention has been described with reference to certain disclosed embodiments, the disclosed embodiments are presented for purposes of illustration and not limitation and other embodiments of the invention are possible. A variety of related methods (e.g., methods of manufacturing, methods of using) are also within the scope of the present invention. One skilled in the art will appreciate that various changes, adaptations, and modifications may be made without departing from the spirit of the invention. 

1. A watercraft comprising: a board having a first side and a second side opposite the first side; and a propulsion system secured to the board, the propulsion system comprising: a water outlet portion; a water intake portion, the water intake portion comprising a rim having a cross-sectional area that tapers along a length of the rim in a direction moving toward the water outlet portion; a first blade having a first end connected to the rim and a second end opposite the first end, the second end being a free floating end; and a first motor located between the water outlet portion and the water intake portion, the first motor having a first rotor component and a first stator component, the first rotor component being configured to rotatably drive the rim.
 2. The watercraft of claim 1, wherein the first blade extends along the length of the rim, and wherein a pitch of the first blade increases along the length of the rim as the cross-sectional area of the rim tapers.
 3. The watercraft of claim 1, wherein the propulsion system further comprises: a second blade having a first end connected to the rim and a second end opposite the first end, the second end being a free floating end, wherein the second blade extends along the length of the rim, and wherein a pitch of the second blade increases along the length of the rim as the cross-sectional area of the rim tapers, the pitch of the second blade being equal to the pitch of the first blade.
 4. The watercraft of claim 1, wherein the propulsion system further comprises: an annular tube extending between the water outlet portion and the water intake portion, the annular tube extending within the first rotor component and coupled to the rim, wherein the first rotor component is configured to rotatably drive the annular tube to thereby rotatably drive the rim.
 5. The watercraft of claim 1, wherein the propulsion system defines a fluid flow path extending through the water intake portion, the annular tube, and the water outlet portion.
 6. The watercraft of claim 5, wherein the fluid flow path extends through the first rotor component and the first stator component.
 7. The watercraft of claim 1, wherein the rotor component is a magnetic rotor assembly.
 8. The watercraft of claim 1, further comprising a second motor located between the water outlet portion and the water intake portion adjacent the first motor, the second motor having a second rotor component and a second stator component, the second rotor component being configured to rotatably drive the rim.
 9. The watercraft of claim 8, further comprising a third motor located between the water outlet portion and the water intake portion adjacent the first and second motors, the third motor having a third rotor component and a third stator component, the third rotor component being configured to rotatably drive the rim.
 10. The watercraft of claim 1, wherein the first side of the board includes a first foot attachment adapted to secure a first foot of a rider to the board and a second foot attachment adapted to secure a second foot of the rider to the board.
 11. A watercraft comprising: a board having a first side and a second side opposite the first side; a first foot attachment on the first side of the board and adapted to secure a first foot of a rider to the board; a second foot attachment on the first side of the board and adapted to secure a second foot of the rider to the board, wherein the first foot attachment and the second foot attachment are spaced apart along a central longitudinal axis of the board; and a block extending out from the first side of the board between the first foot attachment and the second foot attachment, wherein the block extends out a distance from the first side of the board beyond the first foot attachment and the second foot attachment, and wherein the block has a first surface that is adapted to interface with a first leg of the rider and a second surface opposite the first surface that is adapted to interface with a second leg of the rider.
 12. The watercraft of claim 11, wherein the first surface of the block is aligned along the central longitudinal axis of the board with the first foot attachment and the second surface of the block is aligned along the central longitudinal axis of the board with the second foot attachment.
 13. The watercraft of claim 11, wherein the first surface of the block includes a first recessed region and the second surface of the block includes a second recessed region.
 14. The watercraft of claim 11, wherein the first foot attachment is located on a first platform elevated above a deck surface of the first side of the board and the second foot attachment is located on a second platform elevated above the deck surface of the first side of the board.
 15. The watercraft of claim 11, wherein a buoyancy of the watercraft is sufficient to float the watercraft itself in water when stationary but the buoyancy of the watercraft is insufficient to float the watercraft in water with external loading applied when stationary.
 16. The watercraft of claim 15, wherein the board has a width extending perpendicular to the central longitudinal axis of the board, and wherein the width tapers toward a rear portion of the board.
 17. The watercraft of claim 16, wherein the first foot attachment is located at a first portion of the board having a first width and the second foot attachment is located at a second portion of the board having a second width that is less than the first width.
 18. The watercraft of claim 11, wherein the second side of the board includes a water intake and a water outlet spaced along the central longitudinal axis of the board from the water intake, and wherein the second foot attachment is positioned along the central longitudinal axis of the board closer to the water outlet than the first foot attachment.
 19. The watercraft of claim 18, wherein a motor is positioned between the water intake and the water outlet.
 20. The watercraft of claim 10, wherein the block includes a handle extending out from block in a direction opposite the first side of the board, and wherein the second side of the board includes a fin. 